Field of the Disclosure
The present disclosure relates to a method, device and computer software.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in the background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.
In television graphics, chroma keying is used to determine where the television graphic is to be overlaid. This is commonly used in weather reports, where a graphic is overlaid on a blue or green coloured screen (having a particular chrominance value). This system works well in a controlled environment where lighting is consistent. However, where lighting is not consistent, or the colour of the area over which the graphic should be overlaid is not consistent, it is not easy to perform chroma keying.
One example scenario is a sports field. During televised sports games, it is sometimes desirable to overlay a graphic over an area of the sports field. Normally, this would be green (the colour of grass). However, the shade of green varies depending on the cut pattern of the grass and any shadow cast by the stadium in which the sports event is played. Indeed, during the course of the game, the colour of the grass at any one point may change due to a shadow moving or because the grass at that point is damaged and brown soil is exposed. This makes chroma keying difficult in situations where the background colour varies over time. Further, there are colours on players' kits that are present on the pitch. In other words, it is very difficult to determine using conventional techniques which areas are foreground objects and which are background objects. It is an aim of the present disclosure to alleviate this problem.